Chemical and electrochemical biosensors are useful in medicine and chemistry for determining the presence or concentration of analytes. Typically, some biosensors produce signals which are related to the concentration of an analyte. Biosensors are important medical tools because of their ability to measure the concentrations of molecules which are indicative of various conditions, diseases, or disorders, and therefore a patient's need for treatment.
Biosensors may be exemplified by devices which comprise an enzyme layer and utilize electrodes. The electrodes are able to detect chemical species such as oxygen. When enzyme layers attached to the electrodes catalyze a reaction, a chemical is produced. This chemical is detected by a specific electrode. Therefore, it is often important to limit the analytes that may come into contact with the enzyme layer of a biosensor. This task may be achieved by a selectively permeable membrane.
A need exists, however, for better selectively permeable membranes and methods of production. Known conventional membrane materials typically have insufficient adhesion to substrates, poor blocking efficiency to interfering species and/or unsatisfactory dimensional stability. For long term sensors, in particular, instability of the membrane results in more signal drift which necessarily requires more frequent calibration and may cause a reduction in sensor lifetime. It therefore would be desirable to provide membrane materials that reduce or some or all of these deficiencies, particularly for implantable biosensors intended for use over an extended period. In addition, there is a need for such a selectively permeable membrane to be reproducibly manufacturable.